Sudo in a Nutshell

Sudo (su "do") allows a system administrator to give
certain users (or groups of users) the ability to run some
(or all) commands as root while logging all commands and arguments.
Sudo operates on a per-command basis, it is not a replacement
for the shell. Its features include:

The ability to restrict what commands a user may run
on a per-host basis.

Sudo does copious logging of each command, providing a
clear audit trail of who did what. When used in tandem
with syslogd, the system log daemon, sudo can log all
commands to a central host (as well as on the local host).
At CU, all admins use sudo in lieu of a root shell
to take advantage of this logging.

Sudo uses timestamp files to implement a "ticketing" system.
When a user invokes sudo and enters their password,
they are granted a ticket for 5 minutes (this timeout
is configurable at compile-time). Each subsequent sudo
command updates the ticket for another 5 minutes.
This avoids the problem of leaving a root shell
where others can physically get to your keyboard.
There is also an easy way for a user to remove their ticket
file, useful for placing in a .logout file.

Sudo's configuration file, the sudoers
file, is setup in such a way that the same sudoers file
may be used on many machines. This allows for central
administration while keeping the flexibility to define
a user's privileges on a per-host basis. Please see
the samples sudoers file below for a real-world example.

To get a good idea of what sudo can do, you really need
to take a look at a sample sudoers file.
The sudoers manual explains the
syntax in detail.